Gas-jet propelled hemostats for targeted hemostasis in wounds with irregular shape and incompressibility.

Since hemostats are likely to be flushed off a wound by a massive gushing of blood, achieving rapid and effective hemostasis in complex bleeding wounds with powder hemostats continues to be a significant therapeutic challenge. In order to counter the flushing effect of gushing blood, a gas-jet propelled powder hemostat ((COL/PS)4@CaCO3-T-TXA+) has been developed. (COL/PS)4@CaCO3-T-TXA+ dives into the deep bleeding sites of complex wounds for targeted hemostasis. In preparation, protamine sulfate and collagen are first electrostatically deposited on CaCO3, which is then loaded with thrombin, and finally doped with protonated tranexamic acid (TXA-NH3+) to produce the final therapeutic medicine (COL/PS)4@CaCO3-T-TXA+. When applied to bleeding tissues, CaCO3 and TXA-NH3+ from (COL/PS)4@CaCO3-T-TXA+ immediately react with each other in blood to release countless CO2 macro-bubbles, which direct the hemostatic powder, (COL/PS)4@CaCO3-T-TXA+, precisely towards deep bleeding sites from complex wounds. Then the carried thrombin is released to accomplish targeted hemostasis. According to animal studies, (COL/PS)4@CaCO3-T-TXA+ has better effects in rabbit hepatic hemorrhage models; the hemorrhage quickly stops within 30 s, which is roughly 20% less than with the commercial product CeloxTM. The present study provides a new strategy for using powder hemostats to quickly and effectively stop bleeding in complex bleeding wounds.

Dual-Driven Hemostats Featured with Puncturing Erythrocytes for Severe Bleeding in Complex Wounds.

Achieving rapid hemostasis in complex and deep wounds with secluded hemorrhagic sites is still a challenge because of the difficulty in delivering hemostats to these sites. In this study, a Janus particle, SEC-Fe@CaT with dual-driven forces, bubble-driving, and magnetic field- (MF-) mediated driving, was prepared via in situ loading of Fe3O4 on a sunflower sporopollenin exine capsule (SEC), and followed by growth of flower-shaped CaCO3 clusters. The bubble-driving forces enabled SEC-Fe@CaT to self-diffuse in the blood to eliminate agglomeration, and the MF-mediated driving force facilitated the SEC-Fe@CaT countercurrent against blood to access deep bleeding sites in the wounds. During the movement in blood flow, the meteor hammer-like SEC from SEC-Fe@CaT can puncture red blood cells (RBCs) to release procoagulants, thus promoting activation of platelet and rapid hemostasis. Animal tests suggested that SEC-Fe@CaT stopped bleeding in as short as 30 and 45 s in femoral artery and liver hemorrhage models, respectively. In contrast, the similar commercial product Celox™ required approximately 70 s to stop the bleeding in both bleeding modes. This study demonstrates a new hemostat platform for rapid hemostasis in deep and complex wounds. It was the first attempt integrating geometric structure of sunflower pollen with dual-driven movement in hemostasis.

Chestnut-like macro-acanthosphere triggered hemostasis: a featured mechanism based on puncturing red blood cells.

Acute hemorrhage that occurs after trauma is a life-threatening condition. Hence, to halt massive bleeding, there is a critical need to develop a suitable therapy. In this study, we developed self-propelling chestnut-like particles (Pro-MAS) comprising a macro-acanthosphere (MAS) coated with calcium carbonate and protonated tranexamic acid to puncture red blood cells (RBCs) and thus activate hemostasis. In vitro assessments revealed that Pro-MAS was biocompatible, biodegradable, and nontoxic; furthermore, it was capable of puncturing RBCs to release procoagulants and activate platelet aggregation for hemostasis. Animal tests showed that self-propelling Pro-MAS effectively traveled through blood flow to the deep ends of wounds; hemorrhage was controlled within 90 s and 4 min in the injured liver and bleeding femoral artery, respectively. Compared with a commercial hemostat, superior hemostasis was achieved with Pro-MAS, which could be ascribed to its functional and structural features. Overall, traveling Pro-MAS possessed sufficient impact force to puncture RBCs and sufficient momentum to reach the targeted bleeding sites. The present study demonstrated the ability of a novel platform, self-propelling MAS particles, to trigger hemostasis by puncturing RBCs. To the best of our knowledge, this is the first trial in which the release of endogenous procoagulants is promoted without the addition of exogenous procoagulants for severe hemorrhage control.

Flexible, Reusable SERS Substrate Derived from ZIF-67 by Adjusting LUMO and HOMO and Its Application in Identification of Bacteria.

Conventionally, surface-enhanced Raman spectroscopy (SERS)-active materials mainly include nanosized noble metals, semiconductors, or the complex of both, most of which are limited in practical applications because of their symbiotic materials, complex and difficult to control fabrication processes, and reuse and sampling challenges. To address these issues, novel SERS substrates have been developed in this study by anchoring zeolitic imidazolate framework-67 (ZIF-67) and derivatives of ZIF-67 to cotton fabric. The designed SERS substrates show extraordinary flexibility, an excellent enhancement factor, and reusable performance. By adjusting the lowest unoccupied molecular orbital and highest occupied molecular orbital of ZIF-67 through a doping process with different metal ions, the substrates exhibit a high enhancement factor of 6.07 × 106 and a low limit of detection of 10-8 M, as well as reusability resulting from photocatalysis. The enhancement process is studied based on charge transfer resonance, interband transition resonance, ground state charge transfer, and the light coupling effect. The results contribute to the approaches in designing SERS substrates by using ZIFs as unique SERS-active materials, and provide new insights into the development of novel SERS-active materials, along with promoting the use of SERS detection in the real world by improving the flexibility of substrates.

A self-adapting hydrogel based on chitosan/oxidized konjac glucomannan/AgNPs for repairing irregular wounds.

Wound dressings play a critical role in the cutaneous healing process. The uncertainty of an injury leads to an irregular wound. However, incomplete contact between a general dressing and wound reduces the effectiveness of the dressing. Therefore, self-adapting hydrogels that are adhesive, injectable, and self-healable are being developed to efficiently treat irregular skin wounds. Here, we present an approach based on dynamic Schiff-base bond formation to prepare self-adapting hydrogel dressings that automatically adapt to irregular wounds under natural conditions and sustain total contact with the injured site. Spectroscopic investigations suggested the formation of dynamic covalent Schiff-base bonds, which are closely associated with the rapid formation of the hydrogel, between the aldehyde groups of oxidized konjac glucomannan and amine groups in the backbone of protonated chitosan and protonated tranexamic acid. Rheological analysis confirmed the self-healing property of the hydrogel, that is, the recovery of the broken hydrogel network. Histological analysis indicated that this self-adapting hydrogel provides a clear advantage over the commercial hydrogel dressing (AquacelAg™) in the in vivo wound-healing process. Our rapidly gelating hydrogel formulations with self-healing ability, tissue adhesiveness, and antibacterial activity are very promising self-adapting biomaterials for repairing irregular wounds.

Fabrication of silk fibroin/poly(lactic-co-glycolic acid)/graphene oxide microfiber mat via electrospinning for protective fabric.

In this study, a biodegradable silk fibroin/poly(lactic-co-glycolic acid)/graphene oxide (SF/PLGA/GO) microfiber mat was successfully fabricated via electrospinning for use in protective fabrics. The morphology of the microfiber mat was characterized by Scanning Electron Microscope (SEM). The thermal and mechanical properties, water contact angle, surface area and pore size of the microfiber mats were characterized. Due to the introduction of graphene which can interact with silk fibroin, the SF/PLGA/GO microfiber mat, compared with the silk fibroin/poly (lactic-co-glycolic acid) (SF/PLGA) microfiber mat, has higher strength, greater Young's modulus and better thermal stability which can meet the requirements of protective fabric. The microfiber mat is biodegradable because its main component is silk fibroin and PLGA. In particular, the microfiber mat has a small pore size range of 4 ∼ 10 nm in diameter, a larger surface area of 2.63 m2 g-1 and pore volume of 7.09 × 10-3 cm3 g-1. The small pore size of the mat can effectively block the particulate pollutants and pathogenic particles in the air. The larger surface area and pore volume of the mat are effective for breathability. Therefore, the fabricated SF/PLGA/GO microfiber mat has great application potentials for protective fabrics.

Removal of Reactive Dyes in Textile Effluents by Catalytic Ozonation Pursuing on-Site Effluent Recycling.

The textile wash-off process consumes substantial amounts of water, which generates large volumes of wastewater that pose potential pollution issues for the environment. In the present study, catalytic ozonation was applied to degrade residual dyes present in rinsing effluents from wash-off processes towards the aim of recycling the waste effluents. A magnetic catalyst was prepared for promoting dye degradation by catalytic ozonation. Via a hydrothermal reaction, highly magnetic manganese ferrite (MnFe2O4) particles were successfully loaded on carbon aerogel (CA) materials (MnFe2O4@CA). The results showed that the developed catalyst strikingly promoted the degradation of dye contaminants by catalytic ozonation, in terms of color removal and reduction of chemical oxidation demand (COD) in rinsing effluents. COD removal efficiency in catalytic ozonation was enhanced by 25% when compared with that achieved by ozonation alone under the same treatment conditions. Moreover, we confirmed that after catalytic ozonation, the rinsing effluents could be recycled to replace fresh water without any evident compromise in the color quality of fabrics. The color difference (ΔEcmc(2:1)) between fabrics treated with recycled effluents and water was not more than 1.0, suggesting that the fabrics treated with recycled effluents displayed acceptable color reproducibility. Although colorfastness and color evenness of fabrics treated with recycled effluents were slightly poorer than those of fabrics treated with water, they were still within the acceptable tolerance. Therefore, the present study validated that catalytic ozonation was a promising technology for saving water and wastewater elimination in textile dyeing. It provides a feasibility assessment of catalytic ozonation for recycling waste effluents to reduce water dependence in textile production. Furthermore, we show a new perspective in on-site recycling waste effluents by catalytic ozonation and enrich the knowledge on feasible approaches for water management in textile production.

Novel wound dressing with chitosan gold nanoparticles capped with a small molecule for effective treatment of multiantibiotic-resistant bacterial infections.

Wound infection caused by multiantibiotic-resistant bacteria has become a serious problem, and more effective antibacterial agents are required. Herein, we report the preparation of wound dressings using the biocompatible chitosan (CS) as a reducing and stabilizing agent in the synthesis of 2-mercapto-1-methylimidazole (MMT)-capped gold nanocomposites (CS-Au@MMT), with efficient antibacterial effects. The synergistic effects of AuNPs, MMT, and CS led to the disruption of bacterial membranes. After blending with gelatin, crosslinking with tannin acid, and freeze-drying, CS-gelatin (CS-Au@MMT/gelatin) dressing was prepared. It had good mechanical properties as well as efficient water absorption and retention capacities. It exhibited outstanding biocompatibility both in vitro and in a cell-based wound infection model. Moreover, the in vivo rabbit wound healing model revealed that the CS-Au@MMT/gelatin dressing possesses significant antibacterial potential against methicillin-resistant Staphylococcus aureus-associated wound infection. Therefore, the CS-Au@MMT/gelatin dressing described in this study may have huge potential in biomedical applications.

Designing of advanced smart medical stocking using stress-memory polymeric filaments for pressure control and massaging.

Compression treatment for the patients with chronic disorders such as venous ulcers and varicose veins needs the proper and adequate level of pressure sustainability. This has been a great challenge for health practitioners and stocking manufacturers even till today. There is an imperious need of any research, where internal compression pressure can be controlled or readjusted externally. In line with this, for the first time this study is focused mainly to design and optimize the smart stocking structure by integrating the stress-memory polymeric filament as a main load bearing element. Six different structures were employed to prepare the stocking fabric tubes. All the structures were investigated for pressure analysis and studied the effect of physical parameters such as temperature, strain, and leg radius. It is possible to control the level of massage effect by varying the stocking structures. An empirical relationship is derived, which provides the knowledge for how to control the stocking pressure with structural modifications like never done before. The effect of massage function on blood flow velocity in the popliteal vein on lower limb was objectively measured by Doppler ultrasound scanning. This study also sheds the insight of stocking structural modification for pressure control and provide the benchmark for achieving the efficient compression. This advanced stress-memory polymeric filaments based multifunctional compression stocking provides static pressure, massage effect, and easy size fitting in a more controlled manner for smart compression therapy.

Minimizing Freshwater Consumption in the Wash-Off Step in Textile Reactive Dyeing by Catalytic Ozonation with Carbon Aerogel Hosted Bimetallic Catalyst.

In textile reactive dyeing, dyed fabrics have to be rinsed in the wash-off step several times to improve colorfastness. Thus, the multiple rinsing processes drastically increase the freshwater consumption and meanwhile generate massive waste rinsing effluents. This paper addresses an innovative alternative to recycle the waste effluents to minimize freshwater consumption in the wash-off step. Accordingly, catalytic ozonation with a highly effective catalyst has been applied to remedy the waste rinsing effluents for recycling. The carbon aerogel (CA) hosted bimetallic hybrid material (Ag⁻Fe2O3@CA) was fabricated and used as the catalyst in the degradation of residual dyes in the waste rinsing effluents by ozonation treatments. The results indicate the participation of Ag⁻Fe2O3@CA had strikingly enhanced the removal percentage of chemical oxidation demand by 30%. In addition, it has been validated that waste effluents had been successfully reclaimed after catalytic ozonation with Ag⁻Fe2O3@CA. They could be additionally reused to reduce freshwater consumption in the wash-off step, but without sacrificing the color quality of corresponding fabrics in terms of color difference and colorfastness. This study may be the first to report the feasibility of catalytic ozonation in minimization of freshwater consumption in the wash-off step in textile reactive dyeing.

Stress-memory polymeric filaments for advanced compression therapy.

Shape memory polymers are stimulus responsive smart materials that can be applied in several forms such as films, fibers, and foams for a wide range of applications. Novel stress-memory behavior at a fiber level is yet to be uncovered, which would be favorable to control stress in the broad horizon of smart materials for numerous functions. In this work, a semi-crystalline segmented polyurethane was synthesized to prepare filaments/fibres and films. A rational experimental design was established and the stress-memory behavior of both the films and filaments was systematically studied for comparison. Tensile stress-memory programming was performed at three strain levels (20%, 40%, and 60%) to record the memory stress response as a function of temperature with time. The characterization of the thermal and mechanical properties of the stress-memory programmed specimens has objectively proven the reason behind the higher stress response in the filaments than in the films. Melt spinning has induced perfect crystallization with ordered polymer packing and enabled maximum memory stress to be retrieved in the filaments. The evolution of memory stress follows a linear trend with an increase in strain and temperature (r2 = 0.91-1). In addition, pressure related studies were also carried out for smart filament integrative fabrics to realize stress-memory behavior. This unprecedented and novel approach of unveiling the memory behavior specifically at the filament level will enable material scientists to comprehend the fundamental aspects for precise optimization and control of memory stress in smart structures for applications such as compression stockings that require stimuli responsive force.

Self-assembly of polypyrrole/chitosan composite hydrogels.

Hydrogels based on the polypyrrole (PPy)/chitosan (CS) composite are self-assembled and characterized for their electrical and swelling properties. The static polymerization of pyrrole monomer in aqueous solution containing CS is accompanied with the formation of PPy/CS composite hydrogel. The feed order in the reaction process plays a key role in the formation of the hydrogels. The participation of one-dimensional PPy blocks in the formation of the hydrogel network avoids a possible migration of PPy from the hydrogel. The effect of pH and ionic strength on the physical properties of PPy/CS composite hydrogels are investigated in detail. The results indicate that the pH-sensitive PPy/CS composite hydrogels show good water absorbencies in distilled water and saline solution. This method may open a new opportunity for the fabrication of composite hydrogels associating the biomacromolecules and conducting polymers, and the improvement of the comprehensive performance of the resulting products.

Intermolecular interactions between natural polysaccharides and silk fibroin protein.

Fabricating novel functional and structural materials from natural renewable and degradable materials has attracted much attention. Natural polysaccharides and proteins are the right natural candidates due to their unique structures and properties. The polysaccharide-protein composites or blends were widely investigated, however, there are few systematical studies on the interactions between natural polysaccharides and silk fibroin protein at the molecular level. Among various interactions, hydrogen bonding, electrostatic interactions and covalent bonding play important roles in the structure and properties of the corresponding materials. Therefore, the focus is placed on the three interactions types in this review. A future challenge is to create polysaccharide and protein composites or blends with tailored structure and properties for the wide applications.

Facial synthesis of polyaniline/AgCl nanocomposites at the interface of water and ionic liquid.

Uniformly polyaniline/AgCl nanocomposites were prepared at the interface of water and ionic liquid. The morphology and structure of the nanocomposites have been studied by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. The experimental results indicated that highly dispersed polyaniline/AgCl nanocomposites with their size of around 50-100 nm were obtained by the polymerization of aniline and the formation of AgCl at the interface simultaneously. The electroactivity of polyaniline/AgCl nanocomposites was further characterized.

Well-dispersed chitosan/graphene oxide nanocomposites.

Nanocomposites of chitosan and graphene oxide are prepared by simple self-assembly of both components in aqueous media. It is observed that graphene oxide is dispersed on a molecular scale in the chitosan matrix and some interactions occur between chitosan matrix and graphene oxide sheets. These are responsible for efficient load transfer between the nanofiller graphene and chitosan matrix. Compared with the pure chitosan, the tensile strength, and Young's modulus of the graphene-based materials are significantly improved by about 122 and 64%, respectively, with incorporation of 1 wt % graphene oxide. At the same time, the elongation at the break point increases remarkably. The experimental results indicate that graphene oxide sheets prefer to disperse well within the nanocomposites.

Synthesis and characterization of poly(3-methyl thiophene) nanospheres in magnetic ionic liquid.

Poly(3-methyl thiophene) nanospheres with their size ranging around 50-60 nm have been synthesized by simply adding monomers into a magnetic ionic liquid, Bmim[FeCl(4)]. The ionic liquid leads to the formation of uniform nanospheres with a relatively narrow size distribution confined to submicrometer-sized domains. The poly(3-methyl thiophene) nanospheres were characterized by FTIR, Raman and thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) was used to show the morphology of the samples. As compared with the conventional solution polymerization method, the polymerization yield and conductivity of the polymers produced in this magnetic ionic liquid system were improved.